Electric resistance for regulating the candlepower of electric incandescent lamps



G. l. BJERRE. ELECTRIC RESISTANCE 50R REGULATING THE CANDLE POWER OFELECTRIC INCANDESCENT LAM PS APPLICATION JILED IAY 4.192].

Patented sept. 12, 1922.

Patented Sept. 12, 1922.

UNITED STATES PATENT OFFICE.

GRAVERS JACOBSEN BJERRE, OF COPENHAGEN, DENMARK.

ELECTRIC nnsis'rANcn FOR REGULATING THE GANDLEPOW ER or ELECTRIC ,INCAN-.IDESGENT LAMPS. 1

Application filed May 4,

To all whom it may concern Be it known that I, Gnavnns JAcoBsnN Banner,a SLll316Ctof the King of Denmark,

residing at Copenhagen, in the Kingdom of Denmark, have invented certainnew and useful Improvements in Electric Resistances for Regulating theCandlepower of Electric Incandescent Lamps, of which the following is aspecification.

The present invention deals with an electric resistance for theregulation of the candle-power of electric incandescent lamps.

It has previously been proposed to regulate the candle power ofincandescent lamps by making use of a resistance inserted in the circuitof the lamp. Said resistance consisted of some secondary or badlyconducting material, for instance graphite, carborundum-powder or thelike which was placed in an insulated holder in which two electrodes areintroduced, both of which contact with the sandy material, at least oneof which can be moved in such a manner that it can push into thematerial compact it and thereby cause the ohmic resistance of theapparatus to be altered.

It has proved in apparatus of this description that when the movableelectrode is introduced into the powdery material cavities are easilyformed, the shape of which corresponds to that of the end of theelectrode, so that only a very unreliable regulation is obtained,because the electrode does not come gradually into contact with thepowdery material when it is introduced into same, but only suddenlynamely when the electrode fills the cavity in the material.

As a result no accurate regulating of can-. dle power can be obtainedand the regulating is further disturbed by the sandy material, which asa rule forms an adhesive column, breaking apart so that the current isthus cut off and the lamp is extinguished and the state of aggregationof the material is greatly changed.

The present invention ensures a very accurate regulation of the candlepower from darkness to full power, even if the apparatus is subjected toshock when in use.

The desired result is, according to the invention, obtained in thefollowing manner: The holder containing the powdery material is an U- orV-shaped tube the branches of which are directed downwards, and in eachof which branches is inserted an electrode,

branches 2 and 8.

1921. Serial No. 466,650."

the tube. The total ohmic resistance of the sandy -material will thus bealtered by the resistance in the'bent part of the tubebe ing increasedor diminished according as said part is more or less filled with thematerial.

: Further particulars are shown on the drawing which is a side view ofthe apparatus. a

1 is a bent tube made of suitable insulated material. An electrode 4 and5 is introduced into each of the downward directed The ends of theseelectrodes are in the form of pistons sliding in the tubes. The spacebetween the electrodes 4, 5 in the tube is partly filled with a variableresistance consisting of a sandy material, for instance powderedgranite, carborundum or the like secondary or badly con ductingmaterial. One of the electrodes, 4, can by means of a lever8 be moved upand down inside the tube. The cross-sectional variation at the bend willbe ell ected purely by gravity, and the state of aggregation orcoherence will be substantially the same under all conditions ofcross-sectional change. The apparatus works in the following manner: Ifthe electrode l be lowered by means of the lever 8 the sandy material inthe tube branch 2 will move downwards thus causing the surface 6 of thematerial in the bent part of the tube to sink downwards. The currentcarrying part of the section marked wzr on the drawing will therefore bediminished and the ohmic resistance will, consequently, be considerablyincreased, thereby diminishing the current, which latter will becomezero at the moment when the sandy material has sunk so low that the two4 as shown, both electrodes may be moved, by means of levers as shown orby means of screws or the like.

The apparatus can be fixed in the foot of a table lamp or at the switchof the lamp or in any other place in the circuit.

I claim:

1. An electrical resistance comprising a bent tube, a granularresistance, conducting terminals contacting with said resistance andmeans to move at least one of said terminals to vary the cross-sectionof the resistance at the bend of said tube.

2. An electrical resistance, comprising a tube, a granular resistancematerial therein and means to change the conductive cross section of thematerial Without substantially changing the state of aggregation orcoherence of the material.

8. An electrical resistance, comprising a tube, a loose granularresistance material in said tube and means to permit bodilygravitational movement of the material in said tube and thereby diminishthe cross-sectional area of said material.

4. An electrical resistance, comprising a tube, a loose granularresistance material in said tube and means at opposite ends of thecolumn of material in the tube to cause by gravitational action avariation of cross section at one part of said tube.

5. An electrical resistance, comprising abent tube, a granularresistance, conducting terminals contacting with said resistance andmeans to move at least one of said terminals to vary the cross-sectionof the resistance at the bend of said tube.

In testimony whereof I allix my signature.

GRAVERS JACOBSEN BJERRE.

